Compositions comprising a petroleum liquid and an nu-vinyl pyrrolidinaone polymer



United States Patent COMPOSITIONS COMPRISING A PETRGLEUM LIQUllD AND AWN-VENYL PYRROLIDINGNE PGLYMZER La Verne N. Bauer, Cheltenham, Pa.,assignor to Rohm & Haas Company, Philadelphia, Pa, a corporation ofDelaware No Drawing. Filed Mar. 5, 1958, Ser. No. 719,207

16 Claims. (Cl. 252-515) This invention concerns compositions comprisinga liquid petroleum product having dissolved therein at least one polymercontaining units from an N-vinyl pyrrolidinone and from one or moreesters of acrylic or methacrylic acid with or without otherpolymerizable monovinylidene compound. The esters are used inproportions ensuring solubility of the polymer in petroleum liquids, theunits from the N-vinyl pyrrolidinone comprising between 5% and about 30%by weight of the resulting copolymer.

This application is a continuation-in-part of application Serial No.529,585, filed August 19, 1955.

In one type of these compositions a copolymer is dissolved in a fuel oilin an amount suflicient to disperse any gummy or resinous material whichmay form therein. In another type of composition a copolymer isdissolved in an oil having lubricating properties, the amount ofcopolymer present being sufiicient to disperse gums or resins which tendto form therein while in use in combustion engines.

A need has arisen for oil-soluble dispersing agents which are free ofinorganic components which give ash. Such agents could serve to dispersegums, resins, and sludges which form in internal combustion engines as aresult of incomplete combustion of fuel and decomposition of lubricants.

There is a particular need for ashless dispersants which are effectiveat low operating temperatures of gasoline and compression-ignitionengines and under conditions of intermittent service. At the same timesuch a dispersant must withstand conditions of relatively hightemperature operation. It must resist shear and oxidation and becompatible with other additives which are now required in oils, such asanti-oxidants, stabilizers, wearresisting agents, other detergents,especially heavy duty detergents, anti-rust agents, pour pointdepressants, viscosity index improvers, anti-foam agents, or dyes. Itwould be desirable to have agents which can act not only as dispersantsbut also for one or more of the purposes of various other additives anddo so in relatively low proportions. It is desirable also to havedispersants which can be added to petroleum fuels, particularly to fueloils from cracked distillates or fuel oils having an appreciable contentof cracked distillates, and to jet fuels to disperse gums or resinswhich tend to form therein.

Several kinds of polymeric agents have been reported which supplydispersing action in liquid petroleum products. In general these lacksome of the required properties, such as resistance to oxidation orcompatibility with other needed additives or the capacity to supply acombination of properties which permits the use of a minimum number ofadditives and a low proportion of additives.

I have discovered compositions which contain a class of copolymers whichmeet the above requirements very well. They are formed from an N-vinylpyrrolidinone and at least one alkyl acrylate or methacrylate in whichthe alkyl group or groups are of suflicient size to ensure solubility ofthe copolymer in the liquid petroleum product to which it is to beapplied. When the copolymer contains units from an N-vinyl pyrrolidinonein an amount "ice between 5% and 30% by weight, it exhibits dispersingaction against asphaltenes, gums, petroleum resins, and sludges whichform in oils. The preferred content of an N-vinyl pyrrolidinone in thecopolymer is between 6% and 15% by weight and the optimum is from 8% to12% by weight. I

The N-vinyl pyrrolidinones which have been found useful include N-vinylpyrrolidinone itself, 3-methy1-lvinyl pyrrolidinone, 4-methyl-l-vinylpyrrolidinone, 5- methyl-l-vinyl-pyrrolidinone,3-ethyl-l-vinyl-pyrrolidinone, 3-butyl-1-vinyl pyrrolidinone,3,3-dimethyl-1-vinyl pyrrolidinone, 4,5-dimethyl-1-vinyl pyrrolidinone,5,5-dimethyl-l-vinyl pyrrolidinone, 3,3,5-trimethyl-1-vinylpyrrolidinone, 4-ethyl-l-vinyl-pyrrolidinone, S-methyl-S-ethyl-l-vinylpyrrolidinone, 3,4,5-trimethyl-3-ethyl-1-vinyl pyrrolidinone, and otherlower alkyl substituted N-vinyl pyrrolidinones. As is known, these vinylcompounds are available through the reaction of acetylene on the parentpyrrolidinone in the presence of a strong base as catalyst.

The vinyl substituted pyrrolidinones may be represented by the structuretam where the Rs are lower alkyl groups. The preferred N-vinylpyrrolidinones have a total carbon content of not over about ten.

The balance of the copolymer is based primarily upon alkylacrylates ormethacrylates with alkyl groups at least up to octadecyl and ofsuflicient average size to ensure solubility in the liquid petroleumproduct which it is desired to treat. The higher the cut of petroleumproduct in general the greater the need for a larger alkyl group oraverage of alkyl groups. Thus, for use in a fuel oil there may be used aconsiderable proportion of butyl acrylate or methacrylate. Yet about 50%by weight of such butyl ester is about the maximum which can beincorporated into a copolymer with retention of good oilsolubility evenin a fuel oil. The rest of the copolymer would then come from acomonomer having such a group or groups as dodecyl, myristyl, cetyl, orstearyl. Somewhat more hexyl, heptyl, or octyl acrylate or methacrylatecan be used than in the case of the butyl esters to form copolymers ofgood oil-solubility and somewhat less of methyl, ethyl, or propylacrylate or methacrylate. With dodecyl acrylate or methacrylate as thecomonomer the coplymers are generally soluble in all kinds of liquidpetroleum products. This is also true when higher alkyl groups are used.

When 30% to by weight of the copolymer is obtained from cetyl and/orstearyl acrylate and/or methacrylate and there is also used one or moreacrylates or methacrylates with not over 14 carbon atoms in the alkylgroup along with at least 5% of an N-vinyl pyrrolidinone, the resultingcopolymer acts as a pour point depressant in waxy oils as well as adispersant. This is true whether the copolymer of at least the threecomonomers is of relatively low or high molecular weight.

The copolymers of this invention act also as viscosity index improvers.They become in general more effective on this account as the molecularweight of the copolymer increases. With molecular weights increasingfrom about 1,000 to 70,000 or more (number average), improvement in theviscosity index becomes increasingly evident with good to fair stabilityagainst shear. As molecular weights increase about about 70,000,viscosity index will also increase, but with lower shear stability. Nowif the copolymer contains sufiicient units from an acrylic ester withalkyl groups of 16 or more carbon atoms, the copolymer suppliesdispersancy-detergency, viscosity index improvement, and also pour pointdepress1ng action.

While it is preferred to use alkyl acrylates or methacrylates with fourto 18 carbon atoms in the alkyl group or groups, there may also be usedin small proportions silimal alkyl esters but with smaller or largeralkyl groups. It is thus possible to copolymerize a small proportion ofethyl, methyl or propyl acrylate or methacrylate, provided thecombination of polymerizable esters provides the needed solubility inthe oils to be treated, whether fuel or lubricating. The allowableproportion of such lower alkyl groups will depend on the size andproportion of higher alkyl substituents and the petroleum product inwhich the copolymer is to be dissolved.

There may also be used alkyl acrylates or methacrylates with alkylgroups larger than 18 carbon atoms. These are not ordinarily as readilyavailable as cetyl and/or stearyl esters. These larger groups actsimilarly to cetyl or stearyl. There may thus be used trieosyl acrylateor methacrylate or tetracosyl acrylate or methacrylate.

It should also be mentioned that one or more other types ofpolymerizable monovinylidene compounds can be brought intocopolymerization in minor proportions that is, in proportions less thanhalf of the polymerizable monovinylidene compounds other than an N-vinylpyrrolidinone, provided any homopolymer which may form along with thecopolymer does not interfere with the use of the copolymer, as from lackof solubility of the homopolymer in the particular oil being treated andprovided this other monovinylidene compound can in fact enter intocopolymerization.

Some typical comonomers which can be worked into the copolymers of thisinvention in minor amount include dibutyl itaconate, octadecyl butylitaconate, didodecyl fumarate, cetyl butyl fumarate, vinyl acetate,vinyl laurate, vinyl stearate, vinyl octoate, vinyl butyl ether, vinyloctyl ether, vinyl dodecyl ether, vinyl octadecyl ether, vinyltetradecyl thioether, vinyl butyl thioether, styrene, alkylstyrenes,butoxylethyl methacrylate, dodecyloxyethyl methacrylate,dodecyltrioethyl methaerylate, and dimethylaminoethyl acrylate ormethacrylate.

One of the most interesting classes of minor substituents which can beintroduced into the copolymers of an N-vinyl pyrrolidinone and alkylacrylate or methacrylate consists of tert-aminoalkyl acrylates andmethacrylates. N-alkyl groups forming the tertiary amine group areusually methyl or ethyl, but may be propyl or butyl. In their placethere may be used the divalent saturated chains CH2CH2CH2CH2, CH CH CHCH CH or CH CH OCH CH which with the nitrogen form a heterocyele. Thegroup attached to oxygen to form the ester is usually ethylene orpropylene but it may also be larger, as butylene or pentylene.

These aminoalkyl esters may be represented by the formula RCH2=CC-O-CnHz N I ll R R Where C H- is an alkylene chain of at least twocarbon atoms between 0 and N, n is a small integer, usually 2 or 3, R ishydrogen or methyl, and R* and R are lower alkyl (not over butyl) whentaken individually or when taken together a saturated divalent aliphaticchain of 4 to S atoms which jointly with the nitrogen forms amonoheterocyclic amine.

These aminoalkyl esters are valuable comonomers for providing a basicityto the copolymer. They can advantageously provide for about 0.5% toabout of the copolymer. The presence in the copolymer of groups from theaminoalltyl esters improves dispersing action, especially in hightemperature tests, but without the disadvantages which are shown bycopolymers based on just the aminoalkyl acrylates (or methacrylates) andan alkyl acrylates and/or methacrylates. These latter copolymers areusually not compatible with various additives conventionally used inoils. In particular they are not compatible with the petroleumsulfonates which are effective as heavy duty and high temperaturedetergents. Also they are sensitive to oxidation. Yet when theseaminoalliyl esters are used in the copolymers based on an N-vinylpyrrolidinone and tert-aminoalkyl acrylate or methacrylate, they providevery good dispersing action for asphaltenes.

It is necessary that the portion of the copolymers of this inventionderived from one or more acrylic esters have an alkyl portion which onaverage contains at least eight carbon atoms and in any case has analkyl portion of sufficient size to ensure solubility in the petroleumliquid to which the copolymer is to be applied. The average alkyl groupis, of course, calculated on a group or molar basis. The alkyl ester mayhave a single alkyl group of eight or more carbon atoms or there may beused a mixture of acrylates and/or methacrylates, provided there is thisrequired balance of carbon atoms in the alcohol residue.

Copolymers useful in this invention have been described above byreference to the monomers from which they are formed. As has been shown,the copolymers for effective action utilize 5% to 30% by weight of anN-vinyl pyrrolidinone and up to of at least one alkyl acrylate, ormethacrylate, which may be replaced up to half thereof by at least oneother polymerizable monovinylidene compound, the alkyl group or groupsand any other polymerizable monovinylidene compound being selected andbeing proportioned to provide adequate solubility of the copolymer inthe petroleum liquid to be treated. The copolymer, then, is composed of5% to 30% by weight of an N-vinyl pyrolidinone, 36% to 95 of one or morealkyl acrylates or methacrylates (or both), and 0% to 47% of othercopolymerizing monovinylidene compound.

In the following examples which are presented for purposes ofillustration and not for purposes of limitation, there are describedsome typical preparations of copolymers of this invention. In generalthe comonomers are mixed in about the required proportions and aretreated with a polymerization initiator, the resulting mixture ispolymerized, usually by heating. Copolymerization is most convenientlycarried out in a solvent, such as benzene, toluene, xylene, or aromaticnaphtha, or in an oil When a volatile solvent is used, it may bedistilled from the copolymer in the presence of an oil, which thendisplaces the volatile solvent. The resulting solution of copolymer inoil is convenient as a concentrate for addition to the petroleum liquidto be treated.

The polymerization initiator may be any of the usual free radical types,including peroxidic and azo. Typical azo catalysts areazodiisobutyronitrile, dimethylazodiisobutyrate, azodiisobutyramide, andother azo compounds wherein the azo group is acyclic and is preferablybonded to aliphatic carbons, at least one of which is tertiary. Typicalperoxides are benzoyl peroxide, acetyl peroxide, caproyl peroxide,lauroyl peroxide, tert-butyl perbenzoate, di-tert-butyl diperphthalate,2,2-bis(tert-butylperoxy)butane, methyl ethyl ketone peroxide,tert-butyl hydroperoxide, or cumene hydroperoxide. A particularlyeffective initiator system is developed by using a hydroperoxidetogether with a quaternary ammonium salt, such asdiisobutylphenoxyethoxyethyldimethylbenzyl ammonium chloride,lauryldimethylbenzyl ammonium chloride, lauryldimethylcyelohexylammonium chloride, dodecylbenzyltrimethyl ammonium bromide,didodecenyldimethyl ammonium chloride, cetyltrimethyl ammonium chloride,cetylpyridinium chloride, or other quaternary ammonium salts which havealkyl, alkenyl, cycloalkyl, or aralkyl groups as N-substituents. Thequaternary ammonium salt may be used from about 0.01% to 0.5% of theweight of the polymerizing mixture. The salt acts as an activator andhelps to control molecular sizes of the copolymer as well as speeding upthe rate of copolymerization.

Temperatures of polymerization are between 50 and 150 C. Aspolymerization proceeds, addition may be made of initiation solvent orcomonomers, as desired. By adjustment of concentration, temperature,proportion of catalyst, solvent, and time, the copolymers can beprepared in the molecular sizes desired.

Parts are by weight unless otherwise designated.

Example 1 There are mixed 65 parts by weight of an alkyl methacrylatepreparation in which the alkyl portion is obtained from a commercial cutof C to C fatty alcohols, 25 parts of butyl acrylate, and parts ofN-vinyl pyrrolidinone. Thereto, 0.075 part of benzoyl peroxide is addedand the mixture is stirred and warmed to dissolve the peroxide. Additionis made of 20 parts of a white mineral oil to a reaction vessel which isswept out with nitrogen. The mixture of monomers is then slowly addedover a two hour period to this oil. At 2.6 hours, addition is made of0.015 part of benzoyl peroxide. At 4, 4.6, 5.3, and 6 hours, additionsof 0.022 part of benzoyl peroxide are made and during this time anduntil 9-10 hours when heating is discontinued, temperatures aremaintained between 97 and 103 C. At 6.5 hours, 28 parts of white mineraloil is added. The batch is stripped of volatile products by being heatedup to 145 C. at 2 mm. pressure. The yield is about 90% of copolymer. Theproduct is adjusted by addition of oil to copolymer content of 28.5% foraddition to typical oils.

Addition of 0.02% of copolymer to an unstable fuel oil efiectivelyprevents separation of gum or resin when this oil is heated in thepresence of air for six hours. In the absence of this copolymer this oilrapidly forms a resin which plugs a fine screen.

Addition of this copolymer at 1.5% to a 180 neutral, solvent-extracted,Mid-Continent lubricating oil of 95 V.I. and 0 F. pour together with aninhibitor of the zinc dialkyldithiophosphate type and a small amount ofan alkaline earth petroleum sulfonate gives a lubricating compositionwith a rating of 83 in the CRC FL-2 engine test. Without addition ofcopolymer the oil plus other additives gives a rating of 60. The oilcontaining 1.5 of this copolymer has a viscosity index of 140 and a pourpoint of -35 F. The viscosity of this composition is 67 Saybolt seconds(S.U.S.), at 210 F.

The designation CRC above refers to the Coordinating Research Council.The FL-2 is an engine test performed at low temperatures, that is, attemperatures at which moisture may be present in the crank case. Oilsare rated in this test by the extent of deposits on pistons and cylinderwalls.

The above copolymer is highly effective in dispersing asphaltenes in atest based on the Wood River Detergency Test (cf. Talley and Larsen,Ind. Eng. Chem. 15, 915 (1943) A sample of the above preparationadjusted to a 20% copolymer content in a white oil gives a viscosity of216 cs. at 210 F.

Addition of 1% of this copolymer to a 150 Pennsyl- Vania neutral oilhaving a pour point of +25 F. and a viscosity index of 106.9 depressesthe pour point to 30 F. and raises the viscosity index to 130.

Example 2 There are mixed 70 parts of an alkyl methacrylate having alkylgroups of 12 and 14 carbon atoms, 30 parts of N-vinyl pyrrolidinone, and0.8 part of dimethyl azodiisobutyrate. This mixture is slowly added to astirred reaction vessel which is swept out with nitrogen and heated at80 C., two hours being used for this addition. At 2.5 hours addition ismade of 0.32 part of the azodiisobutyrate and 50 parts of toluene. At4.0 hours addition is made of 0.12 part of the azodiisobutyrate and 20parts of rolidinone, but heating is continued for 22 hours.

toluene. At 5 .0 hours there is added 0.05 part of the az'ddiisobutyrate and at 25.5 hours 150 parts of toluene. The yield ofcopolymer is 90.3%. The product is mixed with 163 parts of a mineral oiland the mixture is heated at C. under reduced pressure to removevolatile material, the time of stripping being one hour and the finalpressure 2 mm. of mercury. The concentration of copolymer in oil is36.9%. Adjusted to 30% in oil the solution gives a viscosity of 332 cs.at 210 F.

This copolymer is a very good dispersant for asphaltenes. It is anelfective viscosity index improver. For example, in a Pennsylvanianeutral of +25 F. pour and 107 viscosity index it gives a V.I. of 135 at1% of copolymer with a viscosity at 210 F. of 47 S.U.S. Shear stabilityis at least as good as any commercial methacrylate polymers used as V.I.improvers.

Example 3 A mixture of 70 parts of dodecyl arcylate, 30 parts of N-vinylpyrrolidinone, 0.5 part of benzoyl peroxide, and 30 parts of toluene isslowly added during a two hour period to a stirred reaction vesselheated at 110-120 C. which was blanketed with nitrogen. Heatingthereafter was continued at 90-100 C. At 2.4 hours addition is made of100 parts of toluene and at 4.1 hours of 0.2 part, at 5.3 hours of 0.9part, and at 6.3 hours of 0.37 part of benzoyl peroxide. Total time ofheating is 22.5 hours. The copolymer yield is 98%. The copolymer istransferred in light petroleum oil by heating a mixture of toluenesolution of copolymer and oil to 153 C. under pressures diminishing to 2mm. after 30 minutes. A sample of the copolymer at 30% in toluene givesa viscosity of cs. at 100 F.

This copolymer is a very good dispersant for asphaltenes and sludgesoccurring in used crank case oils. In a 150 Pennsylvania neutral oil of107 viscosity index it gives a V.I. of 128 at 1% and of 138 at2%.

Example 4 In the same way there are mixed 5 parts of N-vinylpyrrolidinone, 95 parts of 99% pure dodecyl methacrylate, 0.5 part ofbenzoyl peroxide, and 15 parts of toluene. The mixture is heated asabove under an inert atmosphere at 116 C. for the first two hours withthe temperature decreasing gradually to 90 C. at the end of 22 hours.During heating additions of benzoyl peroxide amounted to 0.35 part byweight and of toluene of 78 parts. The yield of copolymer is 85%. A 30%solution thereof in toluene has a viscosity of 36.5 centistokes at 100F.

This copolymer exhibits excellent shear stability and fair dispersancy.

Example 5 In the same way there are mixed 85 parts of a stearyl acrylatecontaining some cetyl and lauryl acrylates, 15 parts of N-vinylpyrrolidiione, 20 parts of toluene, and 0.3 part ofazodiisobutyronitrile. The mixture is heated under a nitrogen amtosphereat temperatures between 83 and 95 C. for 8.5 hours. Additions ofazodiisobutyronitrile and toluene are made from time to time, 0.25 partadditional catalyst and 31 parts of solvent being supplied. Time ofheating is 8.5 hours. Yield of copolymer is 92.4%. A 30% solution ofthis copolymer in toluene has a viscosity of 82.2 cs. at 100 F.

This copolymer provides good dispersancy against asphaltenes and fairdispersancy for carbon black. It has excellent mechanical stability. Itgives a moderate increase in viscosity index of typical lubricatingoils. For example, at 2% copolymer in a solvent-extracted Mid- Continentoil of S.U.S. at 100 F. and a V.I. of 97, it increased the V.I. to 126.

Example 6 The same procedure is followed with 75 parts of the same lotof stearyl acrylate and 25 parts of N-vinyl pyr- The yield of copolymeris 95%. A 30% solution of this copolymer in toluene has a viscosity of259.2 cs. at 100 F.

This product is a most excellent dispersant for asphaltenes, crank casesludges, and carbon black. In a +25 F. pour 150 Pennsylvania neutral oilat 0.5% it gives a pour point of +5 F. Shear stability is acceptable. Ithas a favorable action in improving the viscosity index of typical oils.For example, in a 170 S.U.S. at 100 F. solvent-extracted Mid-Continentoil of 97 V.I. it gives a V.I. of 131, at 1% of copolymer and of 141 at2%.

Example 7 There are mixed 65 parts of a cetyl-stearyl methacrylate, 25parts of dodecyl methacrylate, 10 parts of N-vinyl-3- methylpyrrolidinone, 25 parts of toluene, and 0.25 part of diisopropylbenzenehydroperoxide. About half of this mixture is added to a polymerizationvessel equipped with stirrer, blanketed with nitrogen, and heated in anoil bath. The charge is heated to about 100 C. Thereupon 0.125 part ofdiisobutylphenoxyethoxyethyldimethylbenzyl arnmonium chloridemonohydrate dissolved in a little butanol is added. The temperaturerises. The rest of the mixture is gradually introduced into the vesselwith the temperature rising to 115-120 C., at which level it ismaintained for four hours. Temperature is then held at 10l105 C. Smalladditions of toluene are made from time to time and also of thehydroperoxide and the quaternary ammonium salt in butanol. At 6.5 hoursenough toluene is added to bring the copolymer content to about 30%.Total additions of the hydroperoxide are 0.168 part and of quaternaryammonium salt 0.027 part. Heating is discontinued after 7.5 hours. Whenthe toluene solution is adjusted to exactly 30% nonvolatile content, ithas a viscosity of 298 centistokes at 100 F.

This copolymer is transferred to a mineral oil by mixing the toluenesolution with oil and heating the mixture under reduced pressure to anend point of 140 C./ 2 mm. This oil solution also with a 30% copolymercontent is useful for supplying this copolymer to lubricating oils or tofuel oils.

The copolymer provides good dispersancy of asphaltenes in oils. At 1.5in a 180 neutral solvent-extracted Mid-Continent oil of 95 V.I. and F.pour the viscosity index is raised to 142 and the pour point isdepressed to 30 F.

Example 8 The procedure of Example 7 is repeated with a mixture of 88.9parts by Weight of an ester of methaclylic acid and a commercial cut ofhigher alcohols which is essentially a mixture of dodecyl alcohol withsome tetradecyl alcohol, and 11.1 parts of N-vinyl-3-methylpyrrolidinone. The same catalyst and quaternary ammonium salt are used.The copolymer is obtained in a 90% yield. A 30% toluene solution of thecopolymer has a viscosity of 205 centistokes at 100 F. The copolymer islikewise transferred to a white mineral oil as a convenient form foraddition to oils. In a 150 S.U.S. Pennsylvania neutral oil at 33.5% itgives a viscosity of 701 cs. at 210 F.

This copolymer provides very good dispersancy of alphaltenes. It isacceptable in oils subjected to the Indiana oxidation test. In the FL-Zengine test it gives a score of 86 when used in conjunction with aninhibitor of the zinc dialkyldithiophosphate type.

Example 9 There are mixed 80 parts of a lauryl-myristyl methacrylate and20 parts of N-vinyl 3,3,5-trimethylpyrrolidinone and then 0.24 part of adiisopropylbenzene hydroperoxide of 53% hydroperoxide content. There arecharged to a. polymerization vessel parts of toluene, 20 parts of theabove mixture, and a solution of 0.063 part ofdiisobutylphenoxyethyldimethylbenzyl ammonium chloride in 4.5 parts ofbutanol. This charge is heated under nitrogen to about 115 C. The restof the monomer mixture is added in small increments over 1.8 hours.

At 2.6, 4, 4.6, 5.3, and 6.5 hours additions of 5 parts of toluene aremade and at 6.5 hours an addition of 100 parts of toluene is made. Fiveadditions are made of diisopropylbenzene hydroperoxide for a total of0.175 part and of the quaternary solution as above to a total of 1.02parts. Polymerization is continued at about 113-120 C. for four hoursand at 100-105 C. for 3.5 hours. A homogeneous, viscous solution ofcopolymer is obtained which contains 36.4% of non-volatile matter. Atoluene solution of 30% copolymer has a viscosity of 191 centistokes at100 F.

When this copolymer is transferred to an oil and solvent is removedthere is obtained the usual solution in oil. The copolymer providesfairly good dispersancy of asphaltenes.

Repetition of the above procedure with a mixture of 70 parts of the samelauryl-myristyl methacrylate and 30 parts of N-vinyl-3,3,5-trimethylpyrrolidinone leads to a similar copolymer. It gives very gooddispersancy in oils. The higher content of the substituted N-vinylpyrrolidinone seems to give improved results. On the other hand when asmall amount of a tert-aminoalkyl methacrylate is introduced, the amountof substituted N-vinyl pyrrolidinone can be much reduced with retentionof good detergency and of stability.

Example 10 There are mixed parts of a lauryl-myristyl methacrylate, 2parts of dimethylaminoethyl methacrylate, and 8 parts ofN-vinyl-3,3,5-trimethyl pyrrolidinone and then 0.24 part of a 53%diisopropylbenzene hydroperoxide. About a fifth of this mixture is addedto five parts of toluene in a polymerization vessel blanketed withnitrogen. The vessel is heated to about 120 C. and 0.063 part ofdiisobutylphenoxyethyldimethylbenzyl ammonium chloride in 4.5 parts ofbutanol added. The rest of the mixture is introduced to the reactionvessel in small increments. Then additional toluene, hydroperoxide, andquaternary ammonium salt are supplied as in Example 9 with heatingcontinued at 115-120 C. for four hours and -105 C. for the next 3.5hours. A homogeneous viscous solution is obtained containing 37% ofcopolymer. A 30% solution thereof in toluene has a viscosity of 490centistokes at 100 F.

This copolymer is a good dispersant for asphaltenes and gives a score ofabout 81 in the FL-2 test when used in the test oil containinginhibitor. These compositions show good oxidation stability.

The above procedure is carried out with a mixture of 78 parts of thelauryl-myristyl methacrylate, 2 parts of dimethylaminoethylmethacrylate, and 20 parts of N- vinyl pyrrolidinone. The copolymerformed is much like that made just above except for a slight cloudiness.It is a good dispersant for asphaltenes and gives an FL-2 score of 88 inthe test oil containing inhibitor with the copolymer at 1.3% and theinhibitor at 0.65%.

A composition comprising 0.65% of an inhibitor of the zincdialkyldithiophosphate type, 1.5% of this copolymer, and 4.2% (byvolume) of a commercial heavy duty detergent containing analkaline-earth petroleum sulfonate gave an FL-2 rating of 90.

The above procedure is repeated with a mixture of 89 parts of thelauryl-myristyl methacrylate, 3 parts of diethylaminoethyl methacrylate,and 8 parts of 1- vinyl-3,3-dimethyl pyrrolidinone, using the sameweights of 53% of diisopropylbenzene hydroperoxide and quaternaryammonium chloride shown above. The product is a 29.9% copolymer solutionin toluene with a viscosity of 520 centistokes at 100 F. It istransferred to oil in the usual way. When added to fuel oil at 0.001% to0.1%, it acts as a powerful dispersant for gums which tend to formtherein. When added to a lubricating oil, it raises the viscosity indexthereof and supplies dispersancy. In the C.R.C. FL-2 test this productgives a rating of about 85.

The above procedure is again followed with a mixture of 88 parts of thelauryl-myristyl methacrylate, 4 parts of pyrrolidinoethyl methacrylate,and 8 parts of l-vinyl- 3,3-dimethy1 pyrrolidinone. using the sameweights of diisopropylbenzene hydroperoxide and quaternary ammoniumchloride used above. The product is a 30.1% copolymer solution intoluene with a viscosity of 484 centistokes at 100 F. In fuel oil thiscopolymer acts as a dispersant for gums which tend to form therein.After transfer to a light mineral oil this copolymer is applied tolubricating oils with beneficial results. .It raises the viscosity indexof a 170 S.U.S. solvent refined Mid-Continent neutral oil from 97 to 140when the copolymer is used at 1.5%. It is a very good dispersant forasphaltenes.

Similar copolymers are readily prepared in the same way based on analkyl methacrylate in which the alkyl group is of at least 8 carbonatoms or a mixture of alkyl methacrylates, the average carbon content ofthe alkyl groups being at least eight, an N-vinyl pyrrolidinone, and atert-aminoalkyl methacrylate in which the tertiary amine group ispiperidino. The copolymers have the properties described above and forpractical purposes are indistinguishable from those having units frompyrrolidinoethyl and pyrrolidinopropyl methacrylates. Likewise,acrylates can be used instead of methacrylates in forming thetert-aminoalkyl esters.

The above procedure is again repeated but with a mixture of 90 parts ofthe lauryl-myristyl methacrylate, one part of morpholinoethylmethacrylate, and 9 parts of l-vinyl-4,5-dimethyl pyrrolidinone and thesame weights of diisopropylbenzene hydroperoxide and quaternary ammoniumchloride as above. The product is diluted with toluene to a 30%copolymer content. The yield of copolymer is over 90%. The toluenesolution has a viscosity of 489 centistokes at 100 F. The copolymer is agood dispersant for asphaltenes and also for the gums which form in fueloils from cracked stocks.

It is an interesting observation that the various coploymers which havebeen described are compatible with a wide variety of other kinds of oiladditives, including inhibitors, anti-rust agents, stabilizers, pourpoint depressants, anti-foam agents, and heavy duty detergents.

Example 11 There are copolymerized in the same way as in the previousexamples a mixture of 30 parts of a stearyl methacrylate, 35 parts of alauryl-myristyl methacrylate, 25 parts of n-butyl methacrylate, 2 partsof dimethylaminoethyl methacrylate, and 8 parts of N-vinylpyrrolidinone. The yield of copolymer is over 90%. A 30% solutionthereof in toluene has a viscosity of 412 centistokes at 100 F.

The copolymer is transferred to a light petroleum oil as above andincorporated at 1.5% in a 170 S.U.S. solvent refined Mid-Continentneutral oil. There are also used 0.65% of the zincdialkyldithiophosphate inhibitor and 4.2% (by volume) of the abovementioned commercial heavy duty detergent. In an FL-Z test thiscomposition gives a rating of 90+.

In a 36 hour L-4 test for high temperature corrosion and oxidationstability under SAE 30 conditions there is a loss in weight ofcopper-lead hearing as follows: No. 1, 0.05 gram; No. 6, 0.023 gram. Therating is 95.5.

In a single cylinder compression-ignition engine test this compositionshows 3% top ring groove filling in 50 hours, 4.5% TRGF in 75 hours, and6.5% TRGF in 100 hours. The oil plus the same inhibitor plus the samecommercial heavy detergent but with 1.5% of an acrylic ester copolymerfor V1. improvement in place of the above copolymer gives 8.5% TRGF at25 hours and 15% TRGF at 50 hours, and also 2% filling in the secondring groove, after which the test cannot be continued because of ringsticking.

The procedure just above is repeated with a mixture of 30 parts ofstearyl methacrylate, 35 parts of laurylmyristyl methacrylate, 25 partsof butyl methacrylate, 2 parts of dimethylaminoethyl acrylate, and 8parts of N-vinyl pyrrolidinone. Again, the yield of copolymer is over A30% solution in toluene has a viscosity of 421 at F. It is a gooddispersant for asphaltenes and sludge in oils and has propertiesessentially the same as those of the previous copolymer.

For evaluation of the copolymers of this invention in catalyticallycracked furnace oil the Cities Service test (see Analytical Chemistry24, 1959 (1952)) has been used. The oil is subjected to oxidation at 250F. and then passed through a filter with #1 filter paper. The time offiltering is noted. The sample of furnace oil used requires over 2,000seconds for filtering after oxidation. Upon addition of a copolymer from90 parts of a mixture of stearyl, lauryl, and butyl methacrylates inroughly similar weights and 10 parts of N-vinyl pyrrolidinone in aconcentration of 0.01% in the oil a filtering time of 283 seconds isfound. At 0.002% of this same copolymer the filtering time of seconds isobtained.

Tests with another copolymer from 90 parts of a similar mixture ofmethacrylate and 10% of N-vinyl pyrrolidinone gives a filtering time of161 seconds with the copolymer used at 0.005% in the above furnace oil.

This same copolymer applied to a jet fuel at 0.01% which is then heatedto 400 F. and pumped through a filter at 500 F. maintains circulation ofthis fuel oil for over 300 minutes without a measurable increase inpressure. This fuel oil without added copolymer can be circulated foronly 77 minutes before the pressure builds up exorbitantly.

The dispersing action of the copolymers of this invention is obtained infuel oils with about 0.001% to about 0.1% or more by weight of one ormore of the copolymers of this invention. Concentrations above 0.1% areeffective but usually uneconomical, since they are unnecessary.

Fuel oils comprise hydrocarbon distillates boiling from close togasolines up to light lubricating oils. They are variously calledkerosenes, furnace oils, burner oils, Diesel fuels, and jet fuels, thelast including various distillates which may contian some gasoline.

These distillates may be straight-run or cracked oils or mixtures ofsuch oils. In the storage and handling of fuel oils, there may bedevelopment of colors, sludges, and sediments which result in depositsat orifices or on screens and in other parts of equipment for handlingand using these oils.

In lubricating oils dispersing action begins at quite lowconcentrations, but for practical purposes under the conditions of useof these oils, copolymer is generally used between about 0.1% and 20% ofthe weight of the oil, an amount from 0.5% to 5% being preferred.

Lubricating oils include mineral oils varying in viscosity from spindleoils to reciprocating aircraft engine oils. The common oils for sparkingcombustion and compression ignition engines are sold under gradescommonly identified as S.A.E. 10 up through those identified as S.A.E.50 and the like, such engine oils or motor oils being of great but notexclusive importance in the preparation of compositions of thisinvention. These lubricating compositions of this invention also includeautomatic transmission fluids and the like.

I claim:

1. As a new composition of matter, a mineral oil having dissolvedtherein a minor proportion importing dispersing action of a copolymer ofan N-vinyl pyrrolidinone and at least one acrylic ester ROOCC(R =CH theN- vinyl pyrrolidone supplying about 5% to 30% by weight of thecopolymer and R being the alkyl portion of the said ester and ofsutficient size to provide solubility of the copolymer in the oil andhaving an average size of at least eight carbon atoms, in the formula Rrepresenting a member of the class consisting of hydrogen and the methylgroup.

2. As a new composition of matter, a mineral oil having dissolvedtherein a minor proportion imparting dispersing action of a copolymerfrom (1) 5% to 30% by weight of the copolymer of an N-vinylpyrrolidinone, (2) 36% to 95% of at least one acrylic ester of theformula ROOCC(R )=CH wherein R represents the alkyl portion and Rrepresents a member of the class consisting of hydrogen and the methylgroup, the alkyl portion being of sufiicient size and in proportion toprovide solubility of copolymer in a said oil and having an average sizeof at least eight carbon atoms, and (3) to 47% of at least one otherpolymerizable monovinylidene compound selected from the group consistingof alkyl esters, vinyl esters and others, and aminoalkyl esters havingthe formula CH =C(R )COOC,,H NRR*, wherein R is a member of the classconsistin of hydrogen and the methyl group, n is an integer from two tothree, C H is an alkylene chain of at least two carbon atoms and R and Rwhen taken individually are alkyl groups of not over four carbon atomseach and when taken together are saturated divalent chains from thegroup consisting of -CH2CH2CH2CH2, CH2CH2CH2CH2CH2, and CH CH OCH CH 3.A mineral lubricating oil having dissolved therein between 0.1% and 20%by weight of a copolymer from 1) to 30% by weight of the copolymer of anN- vinyl pyrrolidinone, (2) 36% to 95% of at least one acrylic ester ofthe formula ROOCC(R )=CH wherein R represents the alkyl portion and Rrepresents a member of the class consisting of hydrogen and the methylgroup, the alkyl portion being of suificient size and in proportion toprovide solubility of copolymer in a said oil and having an average sizeof at least eight carbon atoms, and (3) 0% to 47% of at least one otherpolymerizable monovinylidene compound selected from the group consistingof alkyl esters, vinyl esters and ethers, and aminoalkyl esters havingthe formula wherein R is a member of the class consisting of hydrogenand the methyl group, n is an integer from two to three, C H is analkylene chain of at least two carbon atoms and R and R when takenindividually are alkyl groups of not over four carbon atoms each andwhen taken together are saturated divalent chains from the groupconsisting of CH CH CH CH 4. A mineral lubricating oil having dissolvedtherein from 0.1% to 20% by Weight of the oil of a copolymer from (1) 5%to 30% by weight of the copolymer of an N-vinyl pyrrolidinone of notover ten carbon atoms and (2) 70% to 95% by weight of the copolymer of aplurality of alkyl methacrylates, 30% to 80% of the alkyl groups thereofhaving chains of 16 to 18 carbon atoms and the rest of the alkyl groupsbeing smaller than sixteen carbon atoms, the average size of alkyl groupbeing sufficient to provide solubility of copolymer in a said oil.

5. A mineral lubricating oil having dissolved therein from 011% to 20%by weight of the oil of a copolymer from (1) 5% to 30% by weight of t ecopolymer of an N-vinyl pyrrolidinone of not over ten carbon atoms, (2)0.5% to of a nitrogenous ester of the formula CH =C(R )COOC H NRR*,wherein R is a member of the class consisting of hydrogen and the methylgroup, n is an integer from two to three, C H is an alkylene chain of atleast two carbons atoms and R and R when taken individually are alkylgroups of not over four carbon atoms each and when taken together aresaturated divalent chains from the group consisting of 12 and (3) in apercentage to make 100% at least one acrylic ester ROOCC(R )=CH R beingthe alkyl portion of sufficient size and in proportion to providesolubility of copolymer in said oil and having an average size of atleast eight carbon atoms, and R being as above defined.

6. A mineral lubricating oil having dissolved therein from 0.5% to 5% ofthe weight of the oil of a copolymer from (1) 6% to 15% by weight of thecopolymer of N-vinyl pyrrolidinone, (2) 0.5% to 10% by weight ofdimethylaminoethyl methacrylate, and (3) a percentage to make 100% atleast one alkyl methacrylate, the alkyl portion of which is ofsufficient size to provide solubility of copolymer in a said oil andhave an average size of at least eight carbon atoms.

7. A lubricating composition according to claim 6 in which the oil is ofa grade used in a spark ignition engine.

8. A mineral lubricating oil having dissolved therein 0.1% to 5% byweight of the oil of a copolymer from (1) 6% to 15% by weight ofcopolymer of N-vinyl pyrrolidinone and (2) 94% to 85% of a plurality ofalkyl methacrylates in which the alkyl groups provide solubility ofcopolymer in a said oil and have an average size of at least eightcarbon atoms.

9. A fuel oil having dissolved therein from about 0.001% to 0.1% byweight of oil of a copolymer of an N-vinyl pyrrolidinone and at leastone acrylic ester ROOCC(R ):CH the N-vinyl pyrrolidone supplying about5% to 30% by weight of the copolymer and R being the alkyl portion ofthe said ester and of sufiicient size to provide solubility of thecopolymer in the oil and having an average size of at least eight carbonatoms, in the formula R representing a member of the class consisting ofhydrogen and the methyl group, and said copolymer imparting dispersingactivity.

10. A fuel oil having dissolved therein from about 0.001% to 0.1% byweight of oil of a copolymer from (I) 5% to 30% by weight of thecopolymer of an N-vinyl pyrrolidinone, (2) 36% to 95% of at least oneacrylic ester of the formula ROOCC(R )=CH wherein R represents the alkylportion and R represents a member of the class consisting of hydrogenand the methyl group, the alkyl portion being of sufi'icient size and inproportion to provide solubility of copolymer in a said oil and havingan average size of at least eight carbon atoms, and (3) 0% to 47% of atleast one other polymerizable monovinylidene compound selected from thegroup consisting of alkyl esters, vinyl esters and ethers, andaminoalkyl esters having the formula CH =C(R )COOC H NR R wherein R is amember of the class consisting of hydrogen and the methyl group, n is aninteger from two to three, C H is an alkylene chain of at least twocarbon atoms and R and R* when taken individually are alkyl groups ofnot over four carbon atoms each and when taken together are saturateddivalent chains from the group consisting of CH CH CH CH CH CH CH CH CHand CH CH OCH CH 11. A fuel oil having dissolved therein from about0.001% to about 0.1% by weight of a copolymer from (1) 5% to 30% byweight of the copolymer of an N- vinyl pyrrolidinone of not over tencarbon atoms and 70% to 95% by weight of the copolymer of a plurality ofalkyl methacrylates, 30% to of the alkyl groups thereof having chains of16 to 18 carbon atoms and the rest of the alkyl groups being smallerthan sixteen carbon atoms, the average size of alkyl group beingsufficient to provide solubility of copolymer in a said oil.

12. A fuel oil having dissolved therein from about 0.001% to about 0.1%by weight of a copolymer from 6% to 15% by weight of copolymer ofN-vinyl pyrrolidinone and (1) 94% to of at least one alkyl methacrylate,the alkyl portion of which is of sufficient size 13 and proportion toprovide solubility of copolymer in a said oil.

13. A fuel oil having dissolved therein from about 0.001% to about 0.1%by Weight of a copolymer from (1) 5% to 30% by weight of the copolymerof an N- vinyl pyrrolidinone, of not over ten carbon atoms, (2) 0.5% to10% of a nitrogenous ester of the formula wherein R is a member of theclass consisting of hydrogen and the methyl group, n is an integer fromtwo to three, C H is an alkylene chain of at least two carbon atoms andR and R when taken individually are alkyl groups of not over four carbonatoms each and when taken together are saturated divalent chains fromthe group consisting of -CH CH CH CH and (3) in a percentage to make100% at least one acrylic ester ROOCC(R )=CH R being the alkyl portionof sutficient size and in proportion to provide solubility of copolymerin a said oil and having an average size of at 100% at least one alkylmethacrylate, the alkyl portion of which is of suificient size toprovide solubility of copolymer in said oil and of an average size of atleast eight carbon atoms.

15. A fuel oil having dissolved therein from about 0.001% to about 0.1%by weight of a copolymer from 1) 5% to 30% by weight of copolymer ofN-vinyl pyrrolidinone and (2) 95% to 70% by weight of at least leasteight carbon atoms, and R being as above defined.

aminoethyl methacrylate, and (3) a percentage to make one alkylacrylate, the alkyl portion being of sufficient size and in proportionto provide solubility of copolymer in a said oil.

16. A mineral lubricating oil having dissolved therein a minor amountfrom about 0.1% to about 20% by weight of an oil-soluble copolymer ofN-vinyl-Z-pyrrolidone with an ester from the group consisting of alkylacrylates and alkyl methacrylates, said alkyl group containing at least8 carbon atoms and the N-vinyl-Z-pyrrolidone supplying about 5% to 30%by weight of the copolymer.

References Cited in the file of this patent UNITED STATES PATENTS2,497,705 Werntz Feb. 14, 1950 2,584,968 Catlin Feb. 12, 1952 2,737,496Catlin Mar. 6, 1956 FOREIGN PATENTS 523,588 Italy Apr. 16, 1955 532,975Belgium Apr. 30, 1955

1. AS A NEW COMPOSITION OF MATTER, A MINERAL OIL HAVING DISSOLVEDTHEREIN A MINOR PROPORTION IMPORTING DISPERSING ACTION OF A COPOLYMER OFAN N-VINYL PYRROLIDINONE AND AT LEAST ONE ACRYLIC ESTER ROOCC(RX)=CH2,THE NVINYL PYRROLIDONE SUPPLYING ABOUT 5% TO 30% BY WEIGHT OF THECOPOLYMER AND R BEING THE ALKYL PORTION OF THE SAID ESTER AND OFSUFFICIENT SIZE TO PROVIDE SOLUBILITY OF THE COPOLYMER IN THE OIL ANDHAVING AN AVERAGE SIZE OF AT LEAST EIGHT CARBON ATOMS, IN THE FORMULA RXREPRESENTING A MEMBER OF THE CLASS CONSISTING OF HYDROGEN AND THE METHYLGROUP.